Plow and conveyor type earth moving machine



April 3, 1956 A. R. HENRY ETAL PLOW AND CONVEYOR TYPE EARTH MOVING MACHINE 5 Sheets-Sheet 1 Filed Nov. 7, 1949 April 3, 1956 A. R. HENRY ET AL PLOW AND CONVEYOR TYPE EARTH MOVING MACHINE 5 Sheets-Sheet 2 Filed Nov. '7, 1949 April 3, 1956 A. R. HENRY ETAL 2,740,211

PLOW AND CONVEYOR TYPE EARTH MOVING MACHINE Filed Nov. 7, 1.949 5 Sheets-Sheet 3 April 3, 1956 A. R. HENRY ETAL 2,740,211

PLOW AND CONVEYOR TYPE EARTH MOVING MACHINE Filed Nov. '7, 1949 5 Sheets-Sheet 4 J? o o INVENTOR.

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April 3, 1956 A. R. HENRY ETAL PLOW AND CONVEYOR TYPE EARTH MOVING MACHINE Filed Nov. 7, 1949 5 Sheets-Sheet 5 1 INVENTOR. Awe/7 flea/y 8%Jf J. 60041? United States Patent PLOW AND CONVEYOR EARTH MOVING MACHINE Albert R. Henry, Salina, Kans., and Ernest s. Coolie, Webster Groves, Mo.

Application November 7, 1949, Serial No. 126,006

1 Claim. (Cl. 37-401) This invention relates to new and useful improvements in earth moving machines, and has particular reference to an earth moving machine suitable for use in the forming of contour ditches or furrows in the earth for the reduction of erosion, commonly known as terracing.

The principal object of the present invention is the provision of an earth moving machine adapted to remove a cut of earth from the ground as the machine is moved forwardly, and to distribute said earth evenly over the ground at either side of the line of travel of the machine.

Another object is the provision, in a machine ofthe character described, of means whereby the distance the earth is moved transversely from the line of travel of the machine may be adjusted at will.

A further object is the provision of a machine of the character described having means whereby a transversely sloping cut may be formed in the earth.

A still further object is the provision of a machine of the character described wherein the earth removed may be elevated or lowered before it is distributed over the ground, thereby adapting the machine for use on sloping ground.

A still further object is the provisionof a machine of the character described having a blade adapted to remove a cut of earth from the ground, said blade being adjustable for depth of cut, a first conveyor adjustable with said blade and adapted to receive earth therefrom, said first conveyor being sloped to elevate said earth, and a generally horizontal second conveyor adapted to receive earth from said first conveyor and being adjustable about a vertical axis, whereby said earth may be moved transversely to the line of travel of the machine.

Other objects are simplicity and economy of construetion, ruggedness and dependability of operation, and adaptability for use in various earth moving operations.

With these objects in view, as well as other objects which will become apparent in the courseof the specification, reference will be had to the drawing, wherein: s

Figure l is a side elevation of an earth moving. machine embodying. the present invention, with partsbroken away.

Figure 2 is a plan View of the machine shown in Fig. 1.

Figure 3 is an enlarged fragmentary section taken on line III-HI of Fig. 2, with parts broken' away.

Figure 4 is an enlarged fragmentary section taken on line -IV'--IV of Fig. 2, withparts broken away. A

Figure 5 is a fragmentary section taken on line V=V of Fi'g. 4. s h p s Figure '6 is a fragmentary section taken on line VI-VI of Fig. 5. V

Figure 7 is an enlarged fragmentary section taken on line VIIVII of Fig. 1, with parts broken away.

Figure 8 is a fragmentary section taken on-line VIII' VI H of Fig. 4.

Figure 9 is a fragmentary section t'akenonline IX-IX of Fig. 4, with parts left in elevation. I k v s Figure I0 is a fragmentary section taken on line X X ot'fi 4,.wi th parts'brokenawa'y. e e I s Figure 11 is a schematic showin of the hydraulic 2 system for powering various operating elements of the machine.

Figure 12 is a partially schematic sectional view showing the operation of one of thehydraulic valves.

Like numbers refer to similar parts throughoutthe several views, and the numeral- 2 applies to the main frame, including two substantially horizontally disposed spaced apart side arms 4 extending parallel to the direction of travel of the machine, said side arms being rigidly connected at their forward ends by a c'ro'ssb'ar '6 and at their rearward ends by a pair of spaced-apart crossbarsj's formed of channel iron. A tongue 10 extends forwardly from crossbar 6, and is provided at it's forward end with an eye 12 suitable for engagement with a tractor or other suitable towing vehicle whereby the machine may be moved over the ground. Said eye is mounted on a pintle 14 carried for axial oscillation in a bearing sleeve 16 fixed to tongue 10 and parallel thereto, whereby the frame 2 may be tilted laterally as hereinafter described.

. Adjacent the forward end of frame 2 an inverted U- shaped member 18 is carried by said frame, the parallel legs thereof being fixed at their lower ends to side-arms 4 and extending upwardly therefrom, and the horizontal upper leg 20 thereof extending between the upper ends of said parallel leg's transversely of the frame 2. Intermediate member 18 and the rearward end of frame 2 is another U-shaped member 22 of greater height than member 18, member 22 being fixed at its lower ends to side arms 4 and having a horizontal tubular leg 24 extending between the upper ends of the parallel legs thereof. Attached rigidly to leg 24adjacent the ends thereof is a pair" of tubular boom members 26. Said boom members converge upwardly and rearwardly, and are rigidly attached at their rearward ends to a vertical bearingsleeve 28. At the rearward end of frame 2, a standard 30 extends upwardly from each side arm 4, and has its upper end portion inclined inwardly and attached rigidly to the adjacent boom member 26, thereby supporting said boom members rigidly.

Boom members 26 are tubular, and are interconnected at their rearward ends as indicated at 32 in Fig'. 4, and are interconnected at theirforward ends to tubular leg 24 of U-member 22, thereby forming a reservoir for the hydraulic system as hereinafter described. This reservoir is indicated generally by the numeral 34 in the diagrammatic view in Fig. '11. Said reservoir is vented to the atmosphere by means of a breatheripipe '36 connected in one of boom member 26 adjacent the rearward'en'd thereof. The portions of standards 30 and member '22 adjacent reservoir 34'are blocked o'if therefrom. Support bars 38 extend between the up erleg 20 of U-shaped-member 18 and a crossbar 40 extendin between the upright "legs of U-shap'ed member. 22. Said support barscarry an internal combustion engine 42 or other suitable power means for driving the conveyors.

A pair of coaxial axles 44 extends transversely to frame 2 beneath and adjacent-the rearward end thereof. Each of said axles is carried rotatably in a bearing 46 fixed to the lower side of the corresponding frame arm 4"and a bearing 48 spaced inwardly from hearing 46 and fixed to 'ero'ssbars 8 by bracing structure '50; Said axles extend outwardly'from the sides of framez, and a'bell-cran'k lever 52' is fixed to the extended end of each axle. Each of said levers has a generally rearwardly'projecting. arm 54 and a generally 'upwardly projecting arm- 56. Fixed in the rearward end of arm-54' i's-a s't-ub axl'e-SS-parallel to axle 44, said stub axle carrying aground engaging wheel 60 for rotation". 'Wheels'60 support substantially the entire weight of the machine. connected by pivot pin '64 said piston rod is connected to the upwardly extending arm 56 of the corresponding bell-crank lever 52 by pivot pin 72. Each of said cylinders is provided with a hydraulic connection 74 by means of which fluid may be introduced into the cylinder to move piston 68 forwardly, and a hydraulic connection 76 by means of which fluid may be introduced into the cylinder to move the piston rearwardly. Since the two cylinders may be operated independently, the elevation of the wheels 60 with respect to the frame 2 may be varied independently, thereby tilting the frame adjustably, transversely to its line of travel.

Disposed between frame side arms 4 is a blade carrier 78 including a pair of struts 80 disposed respectively adjacent the inner surface of each frame side arm 4. Each strut 80 is pivotally connected at its rearward end to the corresponding axle 44 by a bearing 82, said bearing being disposed intermediate axle bearings 46 and 48. At its forward end each strut 80 is provided with a downwardly projecting arm 84 and an upwardly and forwardly projecting arm 86. Rigidly connecting the lower ends of arms 84 is an angle iron crossbar 88, and rigidly connecting the upper ends of arms 86 is a crossbar 90. A mold board 92 is rigidly attached to crossbar 88 intermediate struts 80. Said mold board extends transversely to the direction of travel of the machine, and is inclined forwardly and downwardly. Webbing 94 reinforces the connection of the mold board to crossbar 88. A blade 96, having a transversely extending forward cutting edge, is fixed to the forward edge of mold board 92 by means of bolts 98.

A hydraulic cylinder 100 is pivotally attached at its upper end to a lug 103 fixedly attached to standard 102 which is attached rigidly to and extends upwardly from leg 20 of U-shaped frame member 18, by means of pivot pin 104. Said cylinder carries a piston 106 to which is attached a downwardly extending piston rod 108, said piston rod being pivotally attached at its lower end to a pair of lugs 109 fixedly attached to crossbar 90 of blade carrier 78, by means of pivot pin 110. Cylinder 100 is provided with hydraulic connections 112 and 114 by means of which hydraulic fluid may respectively be introduced into the cylinder to raise or lower piston 106. Thus blade carrier 78 may be pivoted vertically about axles 44 to vary the depth of cut of blade 96.

Two cutting discs 116 are disposed respectively at opposite ends of blade 96. Said discs are inclined forwardly and outwardly, whereby to widen the cut of blade 96, and are adapted to direct the earth cut thereby inwardly to pass over blade 96 and mold board 92. Each of said discs is carried rotatably by a hub 118. An arm 120 is rigidly attached to said hub and extends rearwardly therefrom, being attached at its rearward end to the corresponding strut 80 by means of pivot pin 122 for pivotal movement in a vertical plane. A compression link 124 extends between each disc hub 118 and crossbar 90 of blade carrier 78, as best shown in Fig. 4. Said compression link is of a standard type, and comprises essentially a rod 126 pivoted at one end to lugs on hub 118, at 128, a tubular portion 130 in which rod 126 slides and which is pivoted to lugs fixedly attached to the crossbar 90 at 132. A pin 134 is fixed in rod 126 and extends laterally through a slot 136 formed in tube 130. A spring 138 encircles tube 130 and bears against pin 134 to urge the link resiliently to its extended position. Said compression link is adapted to permit upward movement of discs 116 to pass over stones or other obstructions which they may strike in the ground.

A belt frame 140 is disposed between struts 80 of blade carrier 78. Said belt frame comprises a pair of side rails 142 extending longitudinally of the machine and connected rigidly by crossbars 144. At their forward ends said side rails are provided with hearing members 145 for rotatively supporting a shaft 146 said shaft extending transversely of the machine. A belt roller 148 is mounted on said shaft intermediate side rails 142. Shaft 146 extends outwardly from said side rails, and the extended end portions thereof are journaled respectively in bearings 150 mounted on struts of blade carrier 78 just behind mold board 92. Belt frame is inclined upwardly and rearwardly from shaft 146, and extends rearwardly from the rearward end of main frame 2. At its rearward end, side rails 142 thereof are provided with bearing members 152 for supporting rotatively a shaft 154 parallel to shaft 146. Shaft 154 has a belt roller 156 mounted thereon between side rails 142. A conveyor belt 158 extends around rollers 148 and 156. The upper reach of said belt is supported by spaced rollers 160 carried rotatively by the belt frame. It will be noted that belt roller 148 is so disposed that belt 158 passes immediately beneath the rearward edge of mold board 92, and is adapted to receive earth therefrom. The belt is wider than the mold board, in order to reduce the possibility of earth spilling over the edges of the belt. Furthermore, since the roller 148 is carried by the blade carrier 78, it will remain in proper relationship to the mold board as the blade carrier is adjusted by hydraulic cylinder 100. At its rearward end, belt frame 140 is supported by a pair of links 162, each of which is pivotally connected to one of side rails 142 of the belt frame by pivot pin 164, and which is pivotally connected at its upper end to a stub shaft 166 fixed to one of boom members 26. Each of said links is provided with a turnbuckle 168, for a purpose hereinafter appearing. The pivotal mountings of links 162 permit the slight transverse movement of shaft 154 which occurs when blade carrier 78 is adjusted by means of hydraulic cylinder 100.

A box beam 170 is welded or otherwise rigidly attached to crossbars 8 of frame 2 and extends rearwardly therefrom. A stub shaft 172 extends vertically upwardly from the floor 174 of said beam adjacent the rearward end thereof, as best shown in Figs. 4 and 9, said shaft being mounted in a plate 176 rigidly attached to said beam floor. Said shaft is coaxial with bearing sleeve 28 carried at the rearward ends of boom members 26. Mounted rotatively on said stub shaft by means of a double thrust bearing 178 is a hub 180 which extends upwardly through an aperture 182 in the top wall 184 of beam 170. Affixed to the upper end of said hub is a turntable 186 which covers aperture 182 to prevent the entry of dirt or other foreign matter into the beam. Mounted rigidly on hub 180 within beam 170 is a worm wheel 188. Meshing with said worm wheel is a worm gear 190. Said worm gear is mounted on a shaft 192 which is carried for rotation by bearings 194 mounted on the beam floor 174. Said shaft is attached to and adapted to be driven by any suitable type of reversible hydraulic motor 196, which is also attached to beam floor 174. Said motor is provided with hydraulic connections 198 and 200 through which fluid under pressure may be supplied for respectively driving the motor in either direction.

Mounted rigidly on turntable 186 and rotatable therewith is a carriage 202. Said carriage includes a pair of horizontal crossbars 204 welded or otherwise rigidly fixed to the upper surface of the turntable and extending transversely of the machine, horizontal bar 206 fixed to each end of said crossbars and extending rearwardly longitudinally of the machine, on upright bar 208 extending upwardly from the rearward end of each bar 206, and a bar 210 fixed to the upper end of bars 208. Bars 210 converge upwardly and forwardly and are rigidly fixed at their upper ends to a plate member 212. Rigidly fixed to said plate member is a vertical stub shaft 214, which extends downwardly into bearing sleeve 28 carried by boom 26, and is carried rotatably therein. Thus carriage 202 is carried for axial turning about a vertical axis, and is adapted to be turned by hydraulic motor 196.

Carried by carriage 202 is a belt frame 216 comprising spaced-apart parallel side rails 218 connected rigidly by crossbars 220. Adjacent its forward end ears 222 are rigidly attached to side rails 218 thereof, and said ears are pivotally attached to bearing members 224 mounted on bars 206 of carriage 202, by means of pivot pins 226. Said pivot pins are coaxial on a horizontal axis, and lie in the same vertical plane as axis 'of movement of carriage 202. The belt frame is thus carried for pivotal movement in a vertical planerelative to carriage 202, and is essentially universally pivoted relative to main frame 2.

At the forward end of belt frame 216, side rails 218 thereof are provided with bearing members 228 in which is journaled a shaft 230 parallel to the pivotal axis of the belt frame. At the opposite end of the belt frame, a shaft 232 is similarly carried in bearing members 234 mounted on side rails 218. Belt rollers 236 and 238 are rigidly mounted respectively on shafts 230 and 232 between side rails 2'18, and an endless conveyor belt 240 passes around said rollers. The upper reach of said belt is supported at spaced intervals along its length by a plurality of rollers 242 carried rotatably by belt frame 216 and extending transversely between side rails 218 thereof. Belt 240 extends between uprights 208 of carriage 202, and roller 236 is disposed substantially beneath the rearward end of conveyor belt 158, whereby earth falling from belt 158 as it passes around roller 156 will fall to belt 240 and be conveyed rearwardly thereby. Belt 240 is wider than belt 158,, in order to reduce the spilling of earth over the edges of belt 240. Uprights 288 of carriage 202 are rigidly connected above and below belt 240 by crossbars 244.

Adjacent the rearward end of belt frame 216, an inverted U-shaped yoke 246 is rigidly attached thereto. The parallel side members 248 of said yoke are rigidly fixed at their lower ends to side rails 218 of said belt frame, and the horizontal upper leg 250 of said yoke is spaced above the upper reach of belt 240. A pair of links 252 is pivotally connected to leg 250 in. spacedapart relation by means of pivot pins 254. Said links converge upwardly and forwardly, and are pivoted at their upper ends to a plate member 256 by pin 258. A pair of struts 260 are rigidly connected at their upper ends to plate 256. Said struts diverge forwardly and downwardly, and are respectively pivoted at their lower ends in brackets 262 by pivot pins 264. Said brackets are secured rigidly to uprights 208 of carriage 202. A hydraulic cylinder 266 is pivotally attached at its forward end to plate member212 by pivot pin 268. Said cylinder carries apiston 270 to which is fixed a rearwardly extending piston rod' 272, said piston rod being pivotally connected at its extended end to plate 256 by pivot pin 274. Cylinder266 is-provided with hydraulic connections 276' and 278 through which hydraulic fluid may be introduced into the cylinder for selectively raising or lowering belt frame 216 pivotally about pivot pins 226.

Conveyor belts 158 and 240 are operably driven by the following mechanism: The drive shaft 280 of internal combustion engine 42' extends transversely of the ma chine. To the extended end thereof, at one side of the machine, is fixed a pulley 282, said pulley being operably connected by means of a multiple belt drive 284 with a pulley 286 mounted on a shaft 288 also transverse to the machine. Shaft 288 is disposed above the rearward portion of conveyor belt 158, and is carried for rotation in spaced apart bearings 290 mounted on a bracket 292 fixed to Ushaped members 22 and 30 of main frame 2. A sprocket 294 is fixed on said shaft intermediate said bearings, and is operably connected by chain 296 with a sprocket 298 fixed to the extended end of shaft 154 which carries belt roller 156, whereby conveyor belt 158 is driven. It will be noted that shaft 288 lies substantially in the plane of links 162 which support the rearward end of belt frame 140. One of said links, as best shown in Fig. 6, has a plate 300 fixed therein, said plate having an enlarged aperture 302 formed therethrough through which shaft 288 extends. This permits pivotal movement of links 162 when blade carrier 78 is adjusted as previously described, without. interferring with shaft 188.

Although the pivotal connections 164 and 1166 of :links 162 are not concentric with shafts 154 and 288, and the distance between sprockets 298 and 294 will not be'constant, the variation will not normally be so great as to interfere withthe eificiency of chain drive 296. Furthermore, links 162 may be adjusted by means of turnbuckles 168 to tighten or loosen the chain, if desired.

Attached rigidly to the inner end of shaft 288, and lying substantially in the longitudinal midline of the machine, is a pulley 304, said pulley being operatively connected by multiple belt drive 306 with a pulley 308 mounted on. the vertical input shaft 310 of a gear box-3'12 mounted rigidly on. a bracket 3-14 fixed to bars 2100f carriage 202. Shaft 310 is coaxial with the vertical pivotal axis of carriage 202, and carries within gear box 312 a bevel gear 316 which meshes with another bevel gear 318 carried by a horizontal output shaft 320 journale-d in said gear box. Said output shaft extends rear wardly. A similar gear box 322 is mounted rigidly on one of the side members 248 of yoke 246 which supports the rearward end of belt frame 216. As best shown.

in Fig. 7, said gear box includes an input shaft 324 parallel with the longitudinal axis of belt frame 216. Saidshaft carries a bevel gear 326 meshing with another'bevel gear 328 fixed to an output shaft 330 which extends transversely to the belt frame and parallel to belt roller 23-8. A sprocket 332 mounted on the outwardly extended endv of shaft 230 is operatively connected by chain 334 with a sprocket 336 fixed on the extended end of shaft 232 which carries belt roller 238. A telescoping drive shaft 333 is connected at one end to output shaft 320 of gear box 312 by universal, joint 335, and at its opposite end is connected to input shaft 324 of gear box 322 by universal joint 337. Thus both ofv the conveyor belts are driven from their pulling ends, and the various pulleys, sprockets, and gears in the driving train are so proportioned that conveyor belt 240 will always travel with a speed at least as great as that of belt 158, in order to prevent accumulation of earth on belt 240.

Hydraulic cylinders 62, 100, and 266 and hydraulic motor 196 are operated by the hydraulic systemshown schematically in Fig. 11. A pump 338 is mounted on and driven by internal combustion engine 42. The intake line 340 of said pump connects with fluid reservoir 34, and the pressure line 342 of said valve connects with a composite hydraulic valve 344 mounted on a bracket 346 carried by U-shaped member 18 of main frame 2. As shown in Fig. 11, composite valve 344 comprises five separate and substantially identical valves 348, 350, 352, 354, and 356. Fig. 12 shows a schematic cross-section of valve 348, which controls hydraulic cylinder 100, andserves to illustrate the operation of all of the valves. Said valve comprises essentially a body member 358 having a cylindrical chamber 360 therein, a stem 362 carried slidably by said body member and extending axi ally into said chamber, and a pair of pistons 364 and 36.6v carried on said stem in axially spaced-apart relation. Chamber 368 is provided with a central inlet port 368, and two outlet ports 378 and 372 spaced apart from inlet port 368 longitudinally of chamber 360. Inlet port 368 is interconnected with common pressure line 342 from pump 338, and the outlet ports 370 and 372 are interconnected with conduits 112 and 114 which are in turn respectively connected with the lower and upper ends of cylinder 100. Valve chamber 360 is provided with exhaust ports 374 and 376 at the opposite ends thereof, said ports being joined by passage 378 in body member 358 and interconnected with a common return line 380 which is interconnected with reservoir 34.

When stem 362 is moved to the left, as shown in Fig. 12, fluid from pump 338 flows through line 342 and enters valve chamber 368 through inlet port 368, thence through outlet port 370 and line 112 to the lower end of cylinder 100, whereby piston 106 is forced upwardly. Fluid above the piston is exhausted through line 114, port 372, chamber 360, port 376, passage 378, and line 380 to reservoir 34. When stem 362 is moved to the right fluid under pressure enters valve chamber 360 through inlet port 368, and flows thence through port 372 and line 114 to the upper end of cylinder 100, thereby forcing piston 106 downwardly. Fluid under the piston is exhausted through line 112, port 370, valve chamber 360, port 374, and line 380 to reservoir 34. When stem 362 is moved to a central position, both of ports 370 and 372 are closed, and piston 106 will be locked in position. Each of the hydraulic cylinders 62 and 266, and hydraulic motor 196, are similarly controlled by their respective control valves, valve 354 serving to reverse the flow of fluid to motor 196 to reverse the direction of rotation thereof. Stems 362 of the control valves may be operated manually by any suitable mechanical means, not shown.

The operation of the machine is substantially as follows: A tractor or other towing vehicle is hitched to eye 12, and ground engaging wheels 60 are adjusted vertically relative to frame 2 to the angle of the cut it is desired to make in the ground. This adjustment is made by operating valves 350 and 352 which control the hydraulic cylinders 62. The machine is then towed forwardly, and blade carrier 78 is pivoted downwardly by hydraulic cylinder 100, which is controlled by valve 343, until blade 96 is at the depth desired. The earth cut from the ground moves upwardly over mold board 92 and is deposited on conveyor belt 158, by which it is conveyed upwardly and rearwardly. The earth falls from the rearward end of belt to the forward end of conveyor belt 240. The fall assists in the breaking of clods.

The earth is conveyed rearwardly by belt 240 until it falls therefrom as the belt passes around roller 238. Carriage 202, which supports belt 240, may be turned about a vertical axis by hydraulic motor 196 as previously described, and depending on the angle to which it is turned, the earth carried by belt 240 will be dropped to the ground at various distances from the line of travel of the machine. The worm gear drive by which carriage 202 is turned is self-locking against reverse action; that is, no amount of torque exerted on the carriage by the conveyor can turn the worm gear 190 or load hydraulic motor 196. This removes stress from the hydraulic system. In the event it is desired that conveyor belt 240 should convey earth upwardly along sloping ground, said conveyor may be inclined by hydraulic cylinder 266, which is controlled by valve 356.

Thus it is apparent that we have produced an earth moving machine having several advantages. It is simple, rugged, and has a large earth moving capacity. The depth and angle of cut are freely adjustable, as is the lateral distance which the earth is moved to the side of the line of travel of the machine. It is adapted to perform various types of earth moving functions other than terracing, as for example general grading work or the loading of earth into trucks.

While we have shown a specific embodiment of our invention, it is apparent that many minor modifications of construction could be made without departing from the spirit of the invention.

What we claim is:

In an earth moving machine of the character described, a frame adapted to be towed over the ground, a blade carrier pivoted at its rearward end to said frame and extending forwardly, a blade secured to the foward end of said carrier transvesely to the line of travel of said machine, means carried by said frame for adjustably pivoting said blade carrier for raising and lowering movement, a conveyor belt frame pivoted at its forward end to said blade carrier immediately behind said blade and adjustably supported at its rearward end by said frame, a conveyor belt carried operably by said belt frame and adapted to receive earth from said blade, a pair of ground engaging wheels carried by said frame at opposite sides thereof, independent means carried by said frame for adjusting each of said wheels vertically with respect to said frame, whereby said frame may be tilted transversely to the line of travel thereof to adjust the angle of cut of said blade, an earth cutting disc disposed at each end of said blade, said discs having their planes forwardly divergent to widen the cut of said blade, a pair of hubs each carrying one of said discs for axial rotation, an arm fixed to said hub and extending rearwardly therefrom, said arm being pivoted at its rearward end to said blade carrier for movement in a vertical plane, and a resiliently compressible link pivoted at one end to said hub and at its opposite end to a rigid portion of said blade carrier, whereby said discs may be pivoted upwardly to pass over obstructions in the paths thereof.

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